This is a working document prepared by NIOSH or its contractor for use in discussions with the ABRWH or its 

Working Groups or Subcommittees. Draft, preliminary, interim, and White Paper documents are not final NIOSH or 

ABRWH (or their technical support and review contractors) positions unless specifically marked as such. This 

document represents preliminary positions taken on technical issues prepared by NIOSH or its contractor. 

NOTICE: This report has been reviewed to identify and redact any information that is protected by the 

Privacy Act 5 USC §552a and has been cleared for distribution.

1

WHITE PAPER

Evaluation of Differences in Beta Dose Estimates for GSI

Prepared by David Allen, DCAS

October 10, 2013

Background

In August 2013, NIOSH issued a white paper summarizing dose estimates for GSI. On October 6, SC&A 

issued a response to that white paper that reported a significant difference between NIOSH ansd SC&A 

in beta dose estimates for Betatron Operators. An agreement had previously been reached that NIOSH 

would use the SCA model from its original review of the GSI Site Profile, which was issued in April 2008. 

That model was to be modified using a newer version of MCNPX. This was done for the NIOSH white 

paper so the differences in the two estimates was reviewed and detailed here.

NIOSH did not have the details of the latest SC&A calculation but was able to reproduce the results 

(within 10% for most years). The method used to reproduce those results revealed three primary issues 

contributing to the differences.

1. The uranium working time used in the calculations

Table 1 of the SCA response dated October 6, 2013 lists uranium work hours used by NIOSH and SCA. 

These hours differ and were used by both organizations in calculating beta dose thus represent some of 

the difference in the resulting value. 

2. Error by NIOSH

In comparing the estimated values, it was determined that NIOSH inadvertently used some dose rate 

values from the layout worker rather than the betatron operator.

3. 100% occupancy instead of 50% in original model

Although the above two issues would bring the estimates closer in line, they would not result in a dose 

estimate comparable to the SC&A estimate. However, doubling the dose NIOSH used for exposure to 

irradiated steel results in a reasonable close match. The original SC&A dose estimate that NIOSH agreed 

to use had an occupancy factor where the operator was assumed to be within 1 foot of the irradiated 
This is a working document prepared by NIOSH or its contractor for use in discussions with the ABRWH or its 

Working Groups or Subcommittees. Draft, preliminary, interim, and White Paper documents are not final NIOSH or 

ABRWH (or their technical support and review contractors) positions unless specifically marked as such. This 

document represents preliminary positions taken on technical issues prepared by NIOSH or its contractor. 

NOTICE: This report has been reviewed to identify and redact any information that is protected by the 

Privacy Act 5 USC §552a and has been cleared for distribution.

2

steel 50% of the time (section 2.5 of original SCA review of the Site Profile). It appears that SC&A used 

100% occupancy for its current estimate.

4. Additional issues

There are additional differences in the calculations that NIOSH could not account for. Minor differences 

likely occurred from statistical variability with MCNPX calculations. This does not however, explain all 

the variations. It is our understanding that the same dose rate from the uranium and from steel is to be 

used for all years and the year to year dose estimate would vary only by the uranium work hours. Table 

3 of the SC&A October 6, 2013 memo indicates the 1961 dose estimate is the highest but Table 1 of the 

memo indicates 437.5 hours per year is the highest and is to be used for all years prior to 1958. The 

437.5 hours is applicable to the 7/1/1961 to 6/30/1962 time frame. The work hours prior to and after 

that are lower. Therefore the hours used for 1961 cannot be higher than pre-1958 years and should be 

lower. It is therefore unexplained as to why the 1961 dose estimate is higher than the pre-1958 years.

Below are the corrected NIOSH values. These values have been corrected for the error mentioned in 

item number 2 above.

Table 1

Year Hours per year Hands and Forearms

(rad/yr)

Other Skin

(rad/yr)

10/1/1952 – 1957 337.5 28.5 3.90

1958 337.5 28.5 3.90

1959 337.5 28.5 3.90

1960 337.5 28.5 3.90

1961 387.5 32.0 4.07

1962 281.5 24.5 3.71

1963 76.5 9.9 3.00

1964 28 6.4 2.84
This is a working document prepared by NIOSH or its contractor for use in discussions with the ABRWH or its 

Working Groups or Subcommittees. Draft, preliminary, interim, and White Paper documents are not final NIOSH or 

ABRWH (or their technical support and review contractors) positions unless specifically marked as such. This 

document represents preliminary positions taken on technical issues prepared by NIOSH or its contractor. 

NOTICE: This report has been reviewed to identify and redact any information that is protected by the 

Privacy Act 5 USC §552a and has been cleared for distribution.

3

1965 20.5 5.9 2.81

1966 13 2.7 1.39

Below are the NIOSH values using the uranium working time based on SCA table 1 and doubling the 

steel dose. The SCA values are in parenthesis for comparison. With the exception of the first hand and 

forearm dose, all values are within 10% of each other. 

Table 2

Year Hours per year Hands and Forearms

NIOSH (SCA)

Other Skin

NIOSH (SCA)

10/1/1952 – 1957 437.5 39.4 (33.4) 6.61 (6.27)

1958 366.7 34.5 (32.1) 6.43 (6.22)

1959 337.5 32.4 (30.9) 6.35 (6.18)

1960 337.5 32.4 (30.9) 6.35 (6.18)

1961 387.5 35.9 (34.2) 6.48 (6.30)

1962 281.3 28.5 (27.2) 6.21 (6.04)

1963 76.6 14.2 (13.9) 5.68 (5.56)

1964 28.1 10.8 (10.7) 5.55 (5.45)

1965 20.5 10.3 (10.2) 5.53 (5.43)

1966 12.9 4.9 (4.8) 2.76 (2.71)